Persistence of Microscopic Inflammation Over Endoscopic Remission Does Not Affect Long-Term Crohn’s Disease Outcomes

Mucosal healing (MH) has emerged as a key treatment target in inflammatory bowel disease (IBD) management. Although the latest STRIDE consensus recommends actively pursuing endoscopy-based MH, there are no standardized definitions or formal recommendations for achieving histologic healing. Yet, standardized histologic evaluation through validated scoring systems is scarcely adopted in routine clinical practice. Moreover, the added prognostic value of histologic assessment over endoscopic evaluation alone is still uncertain.

In this prospective observational cohort study, researchers assessed the relationship between endoscopic activity and histologic inflammation (evaluated by the PAID [pattern, activity, interpretation, and dysplasia] scheme) in 749 patients with IBD (60.2% with Crohn’s disease [CD], 38.5% with ulcerative colitis [UC], and 1.3% with IBD-type unclassified [IBD-U]). The role of persistent histologic activity was further explored by comparing the occurrence of major adverse outcomes (MAOs) in patients with concordant or discordant endoscopic and histologic findings.

Of 2807 biopsies, 72.2% were collected from segments without endoscopic inflamma­tion. Among these specimens, 253 exhibited histologic activity, but most activity was mild (90%). Endoscopy accurately identified the presence or absence of mucosal inflammation, reaching a sensitivity, specificity, positive predictive value, and negative predictive value of 70.6%, 90.4%, 75.8%, and 87.5%, respectively.

A higher concordance between endoscopic and histologic scoring was found in UC and IBD-U (>90%) than with CD (79.2%), particularly postoperative CD (76.4%). About 24% of biopsies from apparently normal neo-terminal ileum showed mostly mild inflammation at histologic assessment. However, no association was found between persistent microscopic inflammation and risk of MAOs over 4 years of follow-up in CD.